CHAPTER 12: POPULATION DISTRIBUTION: URBAN LIVING AND SUSTAINABLE CITIES

12-1 URBANIZATION AND URBAN GROWTH

How Fast Are Urban Areas Growing?

Cities have been centers of commerce, communication,
technological developments, education, religion, social change
political power and progress, as well as centers of crowding,
pollution, and disease.

Urban areas have populations of more than 2500 people (some
countries it's 10,000-50,000) and a rural area is fewer
than 2500 people. Degree of urbanization is the percentage
of a population living in an urban area. Urban growth is
the rate of increase in urban populations. By 2025;the
number of people living in urban areas is projected to
reach 5.5 billion, with 90% of this urban growth to occur
in developing countries.

Trends in understanding the problems and challenges of urban growth:
More than 70% of the global population is expected to occur in
urban areas and by 2000 more people will be living in urban
areas than rural areas.

The number of large cities is mushrooming. One person out often
lives in a city with a million people, and many live in the
world's 15 megacities (10 million or more). The urban
population of developing countries is growing at 3.5% per year
and is projected to reach 57% urbanization by 2025, and large
cities already have trouble supplying water, food, housing,
jobs and sanitation. Urban growth in developed countries is
less than 1%, and should reach 84% urbanization by 2025.
Poverty is becoming urbanized as poor people migrate from rural
to urban areas. The United Nations estimates that 1 billion
people live in (1 )crowded . slums of inner cities or (2) in
mostly illegal squatter settlements and .,shantytowns - shacks
on undeveloped land, often unsuitable for human habitation.

In Manila, Philippines, 20,000 people live in shacks built
in city dumps. In 1984, at Bhopal, India, a toxic gas
accident killed 5100 people living in shantytowns near the
factory. In Cairo, Egypt, kindergarten age children can be
found digging through ox dung, looking for undigested
kernels of corn to eat.

Many city governments bulldoze shacks and send
police to drive the illegal settlers out, who then
develop another shantytown somewhere else. Shanty
towns are also found in developed countries, and
most inner cities in the United States have
concentrations of poor.

Despite squalor and disease, most slum
residents are better off than the rural
poor. With access to family-planning, they
tend to have fewer children, who have better
access to schools; a hope for a better
future. A few squatter communities have
organized to improve their living conditions
(Villa El Salvador, Lima, Peru).

What Causes Urban Growth?

Improved conditions in urban areas lower
the death rate, and populations tend to grow, in two ways; natural
increase (more births than deaths) and by immigration (mostly from
rural areas). People are pulled to urban areas in search of jobs and a
better life, or pushed from rural areas by poverty, lack of land,
famine and war.

Modern, mechanized agriculture uses fewer
farm laborers, and allows large landowners
to buy out smaller farmers who cannot afford
to modernize. The urban poor often have to
work long hours for low wages, often in
hazardous conditions.

Case Study: Mexico City

About one of every six Mexicans (15.6
million) live in Mexico City, due to
immigration. Every day 2000 rural peasant
pour into the city, hoping to find a better
way of life. Mexico City has severe air
pollution, high unemployment, congestion and
high crime. More than one-third live in
slums (barrios) without water, electricity,
or sewers. Human waste is deposited in
gutters and the winds pick up dried
excrement, fecal snow that falls on the
city spreading salmonella and hepatitis. Air
pollution from vehicles, factories and
stoves is intensified because Mexico City
lies in a basin, and thermal inversions trap
pollutants at ground level. Plus, engines
burn gasoline less efficiently at the high
altitudes of the city. Breathing the air is
like smoking two packs of cigarettes a day.
Many foreign companies give imported workers
additional "hazard pay" for working in
Mexico City. Mexico City is far from
self-sufficient. Most of the nearby forest
has been cut, cropland has been converted to
urban development, lakes have dried up and
water comes from other water-scarce basins.
The Mexican government is industrializing
other areas in an attempt to slow migration
to Mexico City. Cars have been banned from a
50-block central zone. Unleaded gas began
being phased in 1991, and since 1993, all
new cars must have catalytic converters. The
government planted 25 million trees to help
clean the air.

How Urbanized Is the United States?

There have been three population shifts in
the U.S.: migration to large
central cities - 75% live in metropolitan
areas(50,000 people.) migrating from
large central cities to suburbs and smaller
cities - since 1970
migration from the north and east to the south and west
- 80% of population increase since 1980.

What Are the Major Urban Problems in the United States?

Since 1920, most people have better working
and housing conditions; air and water
quality have improved. Death rates have
dropped, along with malnutrition and
diseases. Concentrating population in small
urban areas has also helped protect the
degradation of wildlife habitat.

The problems facing the cities today are
aging infrastructures (streets, schools,
bridges, housing, sewers), lost tax revenues
as businesses and affluent people move out,
and rising poverty. Violence, drug traffic
and abuse have increased in Some areas.
Unemployment rates are as high as 50% in
Some inner-city areas.

What Are Major Spatial Patterns of Urban
Development?
Three models of urban
structure: concentric-circle city
(New York City) - develops outward from its
central business district (CBD) in a
series of rings as population grows. The CBD
and
inner-city housing are ringed by housing zones that
become more affluent.

sector city (San Francisco to San Jose)-
grows in pie-shaped wedges or strips along
major transportation routes.
multiple-nuclei city (Metropolitan Los
Angeles) - develops around a number of
independent centers (satellite centers).

Separate urban areas may join to form a
megalopolis; Boston and Washington DC
(called Bowash). If a city cannot spread
out, it must grow vertically - upward and
below ground - so it occupies a small area
with a high density. People in compact
cities walk, ride bicycles or use
mass-transit. Heating and cooling costs are
reduces in multistory apartment buildings
(more energy-efficient).

Urban sprawl is automobile-oriented with low
density (cheap gasoline and plentiful land).
People live in single-family houses that
lose heat rapidly. Urban sprawl also gobbles
up natural habitats, farmland and promotes
dependency on the automobile.

12-2 URBAN RESOURCE AND ENVIRONMENTAL PROBLEMS

What Are the Environmental Effects of Urban Areas?

Urban environmental problems can be grouped
into two categories (both are
often found within the same city):
those associated with poverty those
associated with economic growth or affluence:
increases resource use per person

Most cities are not close to being
self-sustaining (import food, water, energy,
minerals), and they produce wastes that pollute air, water
and land. But, they
also have some benefits:
recycling is more feasible (large
concentrations of recycle material)
population growth is reduced
education and mobilization regarding environmental
issues helps preserve biodiversity (reduces stress
on wildlife habitats), but large areas must be
disturbed to provide resources (also become
polluted)

The 43% of the world's urban dwellers occupy
only 5% of the earth's land area. The
harmful environmental impacts varies from
city to city, depending on a city's size and
wealth. Wealthy cities are major
contributors to global problems, while poor
cities can have severe local impacts.

To reach a sustainable relationship between
cities and the living world, cities with a
high-waste, linear metabolism (increasing
resources and wastes) need to convert to
low-waste, sustainable cities with a
circular metabolism.

Why Are Trees and Food Production Important in Cities?

"Most cities are places where they cut down
the trees and then mane the streets after
them." According to the American Forestry
Association, one tree provides over $57,000
worth of air conditioning, erosion and
stormwater control, wildlife shelter, and
air pollution control over 50 years (plus
aesthetic pleasure). Most cities produce
little of their own food, but individuals
can plant community gardens, use window
boxes or gardens on roofs of apartments.
Farmers' markets allow farmers to sell
directly to consumers.

What Are the Water Supply Problems of Cities?

Most cities have water supply and flooding
problems:
to meet demand expensive reservoirs and
canals must be build transfer of
water from rural areas deprives wild areas
of surface water and can deplete
groundwater
concrete and asphalt causes run-off (overloads sewers
and causes flooding) many cities are built on
floodplains (flat, accessible, near rivers) coastal
cities could be flooded if sea level rises

What Are the Pollution Problems of Cities?

Urban residents are generally subjected to
higher concentrations of pollutants:
litter and garbage accumulate in slums
(spread of disease)
1.1 billion live in areas where air pollution exceeds
healthful levels two-thirds of residents in developing
countries do not have adequate sanitation facilities
(water purification and wastewater treatment) and 90%
of all sewage is discharged directly into rivers, lakes
and coastal waters 220 million do not have safe
drinking water (buy from expensive vendors)

Heat islands can merge as urban areas grow
and merge, which affects climate and keeps
polluted air from being diluted. Cities can
counteract the heat-island effect by
tree-planting, lighter (more reflective)
paints, adding sand to asphalt (more
reflective), and energy-efficient standards
for cars, buildings and appliances.

How Serious is Urban Noise Pollution ?

Nearly half of all Americans are regularly
exposed to noise pollution -unwanted ,
disturbing, or harmful sound that impairs or
interferes with hearing, causes stress,
hampers works efficiency, or causes
accidents. Noise is the most widespread
occupational hazard.

Sound pressure is harmful at 75 dbA, painful
at 120 dbA and can kill at 180 dbA
(logarithmic scale). Levels are harmful if
you have to raise your voice to be heard, a
noise causes your ears to ring, or speech
seems muffled.. There are 5 ways to control
noise.
moderate activities and devices to produce
less noise
shield noisy devices
shield workers from the noise
move noisy things away from people
use antinoise - technology that cancels out one
noise with another

How Does Urban Life Affect Human Health?

Some benefits or urban life include better
access to education, social services, and
medical care. But, high-density city life
can increase the spread of infectious
diseases, physical injuries (industrial and
traffic accidents) and health problems
caused from exposure to pollution and noise.
In developing countries many people lack
safe drinking water and or sanitation, and
therefore live and work in life-threatening
environments.

How Does Urban Growth Affect Nearby Rural Areas and Small Towns?

Each year, about 526,000 hectares of rural
land is converted to urban development,
rights-of-way, highways and airports. This
agricultural or forestland is lost for food
production. More energy is needed to
transport food, which causes more pollution.
Urban growth destroys wetlands in coastal
areas. As land becomes more valuable,
increased taxes force many farmers to sell
their land, often to developers. Suburbs
must raise taxes to meet the demands for new
public services and long-rime residents may
be forced out. Old and new residents may
eventually face the inner-city problems they
sought to avoid (harmful positive feedback).